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M.H. Kuehn, C.Y. Kim, Y.H. Kwon; Identification of Steroid–Responsive Genes in Organ Cultured Human Eyes . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3709.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: The mechanisms through which corticosteroids induce ocular hypertension remain unresolved. Previously published studies have demonstrated that cultured trabecular meshwork cells exposed to dexamethasone exhibit distinct changes in their gene expression profile. However, findings derived from cultured cells are not necessarily an accurate representation of the events occurring in an organ composed of various distinct cell types such as the iridocorneal angle. The purpose of the present study was to identify gene expression changes induced by steroids in perfusion organ cultures of human segments. Methods: Human donor eyes were maintained in a perfusion organ culture system. One eye from each pair was perfused with culture media containing 100 nM dexamethasone while the fellow eye was maintained as a control. The pressure inside the culture chamber was recorded continuously. Ten days after exposure to dexamethasone the trabecular meshwork and the underlying limbal tissue was harvested and gene expression patterns were determined through microarray analyses. Results: Data obtained from three pairs of cultured eyes whose pressure did not increase in response to dexamethasone demonstrated that the expression of over 300 genes is modulated by dexamethasone. Among those induced were molecules previously associated with steroid response of trabecular meshwork cells such as MyoC (increased 6.2 fold), as well as those associated with Schlemm’s canal endothelial cells, such as the tight junction proteins TJP1 (increased 1.8 fold) and TJP2 (increased 2.7 fold). Decreased expression levels were observed for a variety of cell–cell signaling, intracellular signal transduction and extracellular matrix molecules. Conclusions: As expected, dexamethasone exposure to the human anterior segment resulted in altered transcript levels of a large number of genes. The eyes utilized in this study did not develop increased intraocular pressure (IOP) and thus it is likely that the vast majority of the observed gene expression changes represent normal physiological responses to steroid exposure and are unrelated to the regulation of IOP. We are currently performing similar analyses using eyes that did display increased IOP in an effort to identify those genes differentially regulated in the iridocorneal angle of steroid–responsive and non–responsive eyes.
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